Centrifugal fan

ABSTRACT

A centrifugal fan is provided. The centrifugal fan includes a main plate connected to a rotational shaft of a motor, a shroud having a suction opening, through which air is introduced, a plurality of blades arranged between the main plate and the shroud, and a rim formed by bending an outer circumference of at least one of the main plate or the shroud in a longitudinal direction of the rotational shaft, the rim portion having an inclination.

This application claims priority to International Patent Application No. PCT/KR2014/003920 filed on May 2, 2014, which claims priority to Korean Application No. KR 2013-0050745 filed in Korea on May 6, 2013, whose entire disclosures are hereby incorporated by reference.

BACKGROUND

1. Field

A centrifugal fan is disclosed herein.

2. Background

A centrifugal fan is a device that discharges air in a circumferential direction from inside of a plurality of blades under the influence of a centrifugal force via rotation of the plurality of blades. Centrifugal fans do not require a duct because air is naturally introduced in an inward direction and discharged in an outward direction. Centrifugal fans are frequently applied to relatively large products, such as a ceiling attachment type air conditioner or similar devices.

FIG. 1 is a perspective view of a conventional centrifugal fan 40. Referring to FIG. 1, in the conventional centrifugal fan 40, to endure stress of high static pressure and high air volume, generally, a shroud 45 has a thickness of 2.5 mm and a main plate 43 has a thickness of 4.5 mm. However, these thicknesses problematically cause excessive material costs and management inconvenience, and power consumption increases due to heavy weight.

SUMMARY

It is one object to reduce thicknesses of a main plate and a shroud while increasing rigidity of the same.

It is another object to increase performance of a centrifugal fan by reducing weights of a main plate and a shroud.

Objects are not limited to the aforementioned objects and other objects not mentioned herein will be clearly understood from the following description by those skilled in the art.

In accordance with one embodiment, the above and other objects can be accomplished by the provision of a centrifugal fan including a main plate connected to a rotating shaft of a motor, a shroud having a suction opening through which air is introduced, a plurality of blades arranged between the main plate and the shroud, and a rim portion acquired by bending an outer circumference of at least one of the main plate and the shroud, the rim portion having an inclination.

In accordance with another embodiment, there is provided a centrifugal fan including a shroud having a suction opening through which air is introduced, a main plate connected to a rotating shaft of a motor, a plurality of blades arranged between the main plate and the shroud, and a corner portion formed at the main plate and/or the shroud to come into contact with air discharged between the plural blades, the corner portion being an angled portion located the same distance from a rotation center.

Details of other embodiments are included in the following detailed description and the drawings.

According to embodiments, one or more effects as follows are accomplished.

Firstly, material cost may be advantageously reduced owing to increased rigidity.

Secondly, reduced thicknesses of a shroud and a main plate may advantageously result in reduced power consumption.

Thirdly, a centrifugal fan having a reduced weight may advantageously achieve increased efficiency.

Fourthly, rigidity of the centrifugal fan may be increased via a relatively simple process.

Effects of the embodiments are not limited to the aforementioned effects and other effects not mentioned herein will be clearly understood from the claims by those skilled in the art.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a conventional centrifugal fan;

FIG. 2 is a perspective view showing a centrifugal fan according to one embodiment;

FIG. 3 is a longitudinal section view showing an outer circumference and a rim portion of the centrifugal fan according to one embodiment;

FIGS. 4A-4B are a perspective view and a longitudinal sectional view of a main plate according to one embodiment; and

FIGS. 5A-5B are a graph showing performance of the centrifugal fan according to one embodiment and performance of a centrifugal fan according to the related art.

DETAILED DESCRIPTION

Advantages and features and a method of achieving the same will be more clearly understood from embodiments described below in detail with reference to the accompanying drawings. However, embodiments are not limited to the following embodiments and may be implemented in various different forms. The embodiments are provided merely to complete disclosure and to provide those skilled in the art with the category of the invention. The invention is defined only by the claims. Wherever possible, the same reference numbers will be used throughout the specification to refer to the same or like parts.

Hereinafter, embodiments will be described with reference to the accompanying drawings to explain a centrifugal fan according to the embodiments of the present invention.

FIG. 2 is a perspective view showing a centrifugal fan according to one embodiment. FIG. 3 is a longitudinal section view showing an outer circumference and a rim portion of the centrifugal fan according to one embodiment.

Referring to FIGS. 2 and 3, the centrifugal fan 1 according to one embodiment includes a main plate 3 connected to a rotational shaft of a motor; a shroud 5 having a suction opening 5 a through which air is introduced; a plurality of blades 7 arranged between the main plate 3 and the shroud 5; and a rim portion or rim 10 acquired by bending an outer circumference of at least one of the main plate 3 or the shroud 5, such that the rim portion 10 has an inclination.

The shroud 5 has the suction opening 5 a. A bell mouse (not shown) may be inserted into and fixed in the shroud 5. The bell mouse serves to guide air to the suction opening 5 a. A diameter of the bell mouse is reduced with decreasing distance to the suction opening 5 a. The shroud 5 is spaced apart from the bell mouse so as to be rotated while maintaining a gap with the bell mouse. The bell mouse is inserted through the suction opening 5 a. A lower end of the shroud 5 is connected to the blades 7.

The main plate 3 is connected to the motor, which applies a torque. The rotational shaft of the motor is connected to the main plate 3.

The plurality of blades 7 is arranged between the main plate 3 and the shroud 5. The plurality of blades 7 may be radially arranged or may be spirally arranged. The plurality of blades 7 is spaced apart from one another. The plurality of blades 7 may be arranged at a constant interval. Each blade 7 defines an air inlet for introduction of air and an air outlet 9 for discharge of air with the other neighboring blades 7. The air inlet is open toward a rotational axis. That is, the air inlet is open toward the center of the main plate 3. The air outlet 9 is open toward a circumference of the main plate 3. Air introduced through the suction opening 5 a passes through the air inlet and is discharged from the air outlet 9.

The rim portion 10 may be formed at the main plate 3 and/or at the shroud 5. The rim portion 10 is bent by a predetermined inclination. The rim portion 10 is formed by bending the main plate 3 and/or the shroud 5 in a longitudinal direction of the rotational axis such that an outer circumference thereof is inclined. Distances d1 and d2 from an extension of the rotational axis O-O′ to the rim portion 10 may be equal.

Bending of the rim portion 10 according to one embodiment is implemented by plastic working. Plasticity is the nature of a material that is permanently deformed upon receiving an external force, rather than returning to an original state thereof, even after removal of the external force. The shroud 5 and the main plate 3 are formed of a plastic deformable material. For example, the shroud 5 and the main plate 3 are formed of a metal sheet or sheet metal.

Plastic working is a processing method using plasticity. Pressing is a processing method for implementation of compression, deformation, shearing, bending, deep drawing or the like using various press machines. The shroud 5 and/or the rim portion 10 may be formed by pressing. The rim portion 10 may be formed by bending.

The rim portion 10 according to one embodiment is bent in a diagonal direction. The rim portion 10 has different upper and lower diameters. A diameter of one end of the rim portion 10 may be less than a diameter of the other end, as the diameter of the rim portion is gradually increased from one end to the other end. The rim portion 10 may have a tapered side cross section.

The rim portion 10 according to one embodiment may have a constant bending angle. The rim portion 10 may be bent by a constant angle. The rim portion 10 may have a constant height.

A bending angle of the rim portion 10 according to one embodiment may be 45 degrees. Although a side surface of the rim portion 10 may have various inclination angles, the side surface may be inclined by 45 degrees. The side surface of the rim portion 10 may be a tapered surface having an angle of 45 degrees. The bending angle may be an angle between the extension of the rotation axis O-O′ and a bending direction of the rim portion 10. The bending angle may be an angle between a plane perpendicular to the extension of the rotational axis O-O′ and the rim portion 10.

According to one embodiment, two rim portions 10 are formed, respectively, at the main plate 3 and the shroud 5, and the rim portions 10 are bent in different directions. The suction opening 5 a is formed at a center of the shroud 5. The shroud 5 may include a protrusion 21 that protrudes toward the bell mouse and internally defines the suction opening 5 a. The shroud 5 may further include an expanded portion 23 connected to the protrusion 21, the plurality of blades 7 being erected downward from the expanded portion 23. The rim portion 10 may be located at an end of the expanded portion 23.

The rim portions 10 may include a shroud rim portion 11 that defines an outer circumference of the shroud 5 and a main plate rim portion 13 that defines an outer circumference of the main plate 3. The shroud rim portion 11 is located at the end of the expanded portion 23. The end of the expanded portion 23 is connected to the shroud rim portion 11. The shroud rim portion 11 may be erected in a protruding direction of the protrusion 21. An inner end of the expanded portion 23 is connected to the protrusion 21 and an outer end of the expanded portion 23 is connected to the shroud rim portion 11. The expanded portion 23 may be curved so as to be connected to the protrusion 21. As a curvature of the expanded portion 23 is reduced outward, the expanded portion 23 may become almost flat with decreasing a distance to the outer end thereof.

The centrifugal fan 1 according to one embodiment has the air outlet 9 for discharge of air between the main plate 3, and the shroud 5 and the rim portion 10 is bent outward of the air outlet 9 so as not to prevent flow of air discharged through the air outlet 9. Air is introduced through the suction opening 5 a and discharged outward through gaps between the plurality of blades 7. The air outlet 9 is defined between the main plate 3 and the shroud 5. The outer circumferences of the main plate 3 and the shroud 5 define the air outlet 9.

The shroud 5 and the main plate 3 according to one embodiment have a same thickness. The shroud 5 and the main plate 3 may be formed of a same sheet. According to one embodiment, a thickness of the shroud 5 and the main plate 3 may be 1.6 mm.

The rim portion 10 according to one embodiment protrudes in a circular form. The rim portion 10 may protrude in a predetermined direction and have a circular shape. The rim portion 10 is bent to achieve a desired height. The rim portion 10 may have different upper and lower diameters. The shroud rim portion 11 includes a first border portion that defines the outer circumference of the shroud 5, and a first connection portion connected to the expanded portion 23.

The main plate rim portion 13 includes a second border portion that defines the outer circumference of the main plate 3, and a second connection portion connected to a mounting portion 31. A diameter of the first border portion may be greater than a diameter of the first connection portion, and a diameter of the second border portion may be greater than a diameter of the second connection portion. The diameter of the first connection portion and the diameter of the second connection portion may be equal to each other. The diameter of the first border portion and the diameter of the second border portion may be equal to each other.

The centrifugal fan 1 according to one embodiment includes the shroud 5 having the suction opening 5 a through which air is introduced; the main plate 3 connected to the rotational shaft of the motor; the plurality of blades 7 arranged between the main plate 3 and the shroud 5; and a corner portion 15 formed at the main plate 3 and/or the shroud 5 to come into contact with air discharged between the plurality of blades 7, the corner portion being an angled portion located a same distance from the rotational center O-O′.

The air outlet 9 for discharge of air is defined between the main plate 3 and the shroud 5. The air outlet 9 is defined between the outer circumference of the main plate 3 and the outer circumference of the shroud 5. The corner portion 15 is located farther away from the rotational center than the plurality of blades 7.

The corner portion 15 is formed at a distal end of the rim portion 10. The corner portion 15 is a connection portion between the rim portion 10 and the expanded portion 23. The corner portion 15 is also a connection portion between the rim portion 10 and the mounting portion 31. The corner portion 15 may be angled by 45 degrees or 135 degrees. A distance from the rotation center O-O′ to the corner portion 15 may be designated by d1 or d2. The corner portion 15 formed at the shroud 5 may be located the same distance d1 from the rotational center O-O′.

The corner portion 15 formed at the main plate 3 may be arranged the same distance from the rotational center O-O′. The corner portion 15 is circularly formed about the rotational center O-O′. A radius of a circle defined by the corner portion 15 may be d1 or d2. Here, d1 and d2 may be equal.

FIGS. 4A-4B are a perspective view and a longitudinal sectional view of a main plate according to one embodiment. Referring to FIGS. 4A-4B, the main plate 3 according to one embodiment includes a boss portion 33 connected to the rotational shaft; and the mounting portion 31 connected to the boss portion 33, the plurality of blades 7 being erected from the mounting portion and the rim portion 10 being placed around the mounting portion. The boss portion 33 protrudes toward the suction opening 5 a.

The mounting portion 31 is connected to the plurality of blades 7. Upper ends of the plurality of blades 7 are connected to the shroud 5 and lower ends of the plurality of blades 7 are connected to the main plate 3. The boss portion 33 is connected to the rotational shaft. The boss portion 33 may protrude toward the motor, or may protrude toward the shroud 5. The mounting portion 31 may be a flat portion. An outer end of the mounting portion 31 may be connected to the rim portion 10. More specifically, the main plate rim portion 13 may be placed at an outer end of the mounting portion 31. The main plate rim portion 13 may protrude in a direction opposite to the boss portion 33. The shroud rim portion 11 may protrude in the same direction as the boss portion 33.

Operation of the centrifugal fan 1 according to embodiments having the above-described configuration will be described below.

The rim portion 10 may be formed by bending a rim of the shroud and/or the main plate. As the rim portion serves to increase rigidity of the shroud and the main plate, the centrifugal fan may be thinner than the conventional centrifugal fan 40. In addition, referring to FIG. 1, although a thickness of the conventional shroud 45 is 2.5 mm and a thickness of the conventional main plate 43 is 4.5 mm, according to one embodiment, thicknesses of the shroud 5 and the main plate 3 may be reduced to 1.6 mm, which results in considerable weight reduction. Accordingly, reduction of material costs and reduction of power consumption due to reduced shaft power are possible.

Meanwhile, the rim portion 10 is formed by plastic working, and thus, has a higher dimensional accuracy than casting. In addition, through improvement in the crystalline structure of a metal, stronger properties than that in casting and cutting processes may be accomplished and higher productivity may be accomplished via mass production of uniform products. In addition, there occurs no generation of chips, differently from cutting, and almost the entire material may be used. In addition, as the rim portion 10 is integrally formed with the shroud 5 and/or the main plate 3 without welding, a clean curved surface may be acquired, which causes reduced flow resistance, resulting in smooth airflow and less flow separation.

FIGS. 5A-5B are a graph showing performance of the centrifugal fan according to one embodiment and performance of a centrifugal fan according to the related art. In FIGS. 5A-5B, a solid line represents performance of the centrifugal fan according to the embodiment and a dotted line represents performance of the centrifugal fan according to the related art. In FIG. 5A showing a static pressure curve, the abscissa represents air volume Q and the ordinate represents static pressure Ps. In FIG. 5B showing an efficiency curve, the abscissa represents air volume Q and the ordinate represents efficiency (%). The efficiency of the centrifugal fan may be calculated by (Air Volume (m³/min)×Static Pressure (mmAq)/(6120×shaft power (kW))×100%.

Referring to FIGS. 5A-5B, the centrifugal fan 1 according to the embodiment has a maximum efficiency of about 79%, the air volume corresponding to the efficiency is about 180 cmm, and the static pressure corresponding to the air volume of 180 cmm is about 120 mmAq. On the other hand, the centrifugal fan according to the related art has a maximum efficiency of about 75%, the air volume corresponding to the efficiency is about 140 cmm, and the static pressure corresponding to the air volume of 140 cmm is about 130 mmAq.

Accordingly, according embodiments, the air volume may be increased by about 30% than that in the related art and the static pressure at the maximum efficiency point may be reduced by about 7% than that in the related art. In addition, since generation of noise is minimized near the maximum efficiency point, the centrifugal fan 1 of the present invention causes less noise than that of the related art based on the same air volume.

Although the exemplary embodiments have been illustrated and described, embodiments are not limited to the above-described particular embodiments, various modifications are possible by those skilled in the art without departing from the scope and spirit as disclosed in the accompanying claims and these modifications should not be understood separately from the scope and spirit. 

1. A centrifugal fan, comprising: a main plate connected to a rotational shaft of a motor; a shroud having a suction opening, through which air is introduced; a plurality of blades arranged between the main plate and the shroud; and a rim formed by bending an outer circumference of at least one of the main plate or the shroud, such that the rim has a predetermined inclination.
 2. The centrifugal fan according to claim 1, wherein the at least one of the shroud or the main plate is formed of a plastic deformable material.
 3. The centrifugal fan according to claim 1, wherein the rim is bent in a diagonal direction with respect to the at least one of the main plate or the shroud.
 4. The centrifugal fan according to claim 1, wherein the rim has a constant bending angle along a circumference thereof.
 5. The centrifugal fan according to claim 5, wherein the bending angle of the rim is approximately 45 degrees.
 6. The centrifugal fan according to claim 1, wherein the rim is formed at each of the main plate and the shroud, and wherein the rim of the main plate and the rim of the shroud are bent in different directions.
 7. The centrifugal fan according to claim 1, wherein the rim is a circular protruding portion.
 8. The centrifugal fan according to claim 1, wherein the rim is formed on the main plate, wherein the main plate includes: a boss connected to the rotational shaft of the motor; and a mounting portion connected to the boss, wherein the plurality of blades is mounted on the mounting portion, wherein the rim extends from the mounting portion, and wherein the boss protrudes toward the suction opening.
 9. The centrifugal fan according to claim 1, wherein an air outlet to discharge air is defined between the main plate and the shroud, and wherein the rim is bent in an outward direction of the air outlet so as not to prevent flow of air discharged through the air outlet.
 10. The centrifugal fan according to claim 1, wherein the shroud and the main plate have a same thickness.
 11. The centrifugal fan according to claim 10, wherein the thickness of the shroud and the main plate is about 1.6 mm.
 12. The centrifugal fan according to claim 2, wherein the at least one of the shroud or the main plate is a sheet metal.
 13. The centrifugal fan according to claim 5, wherein the bending angle is an angle between a plane perpendicular to a rotational axis of the centrifugal fan and the rotational axis.
 14. The centrifugal fan according to claim 1, wherein a side surface of the rim is tapered.
 15. The centrifugal fan according to claim 14, wherein the side surface is tapered at angle of about 45 degrees.
 16. A centrifugal fan, comprising: a main plate connected to a rotational shaft of a motor; a shroud having a suction opening, through which air is suctioned in; a plurality of blades arranged between the main plate and the shroud; and a rim formed on at least one of the main plate or the shroud, wherein the rim is curved in an outward direction with respect to a plane extending in a direction substantially perpendicular to a central rotational axis of the centrifugal fan.
 17. The centrifugal fan according to claim 17, wherein the rim is formed by bending the at least one of the main plate or the shroud in a diagonal direction with respect to the at least one of the main plate or the shroud.
 18. The centrifugal fan according to claim 1, wherein the shroud and the main plate have a same thickness.
 19. The centrifugal fan according to claim 18, wherein the thickness of the at least one of the main plate or the shroud is about 1.6 mm.
 20. The centrifugal fan according to claim 17, wherein a rim is formed on each of the main plate and the shroud and the rims extend in opposite directions. 